The reaction of diisocyanates, polyisocyanates or amine curing agents with alkyd resins, polyester resins, epoxy resins or acrylic resins having hydroxyl groups is used to make coatings for metals and plastics. In conventional coatings, high molecular weight components could be used in solvent solution that make coatings having a broad range of properties. However, solventless or low solvent coatings, which have been developed in response to environmental problems with solvents, must be formed from low molecular weight components which typically make hard coatings that have poor flexibility and poor adhesion to plastics.
Monohydroxlated polybutadienes are known in the art for use in adhesive formulations. U.S. Pat. No. 4,242,468 describes solventless polyurethane coatings having improved flexibility resulting from incorporation of monohydroxylated polybutadienes.
It is an object of the present invention to provide coatings based on resins which contain hydroxyl groups having good flexibility and adhesion to plastics from low molecular weight components.